Infinitely variable transmissions, continuously variable transmissions, methods, assemblies, subassemblies, and components therefor

ABSTRACT

Inventive embodiments are directed to components, subassemblies, systems, and/or methods for infinitely variable transmissions (IVT). In one embodiment, a control system is adapted to facilitate a change in the ratio of an IVT. In another embodiment, a control system includes a carrier member configured to have a number of radially offset slots. Various inventive carrier members and carrier drivers can be used to facilitate shifting the ratio of an IVT. In some embodiments, the traction planet assemblies include planet axles configured to cooperate with the carrier members. In one embodiment, the carrier member is configured to rotate and apply a skew condition to each of the planet axles. In some embodiments, a carrier member is operably coupled to a carrier driver. In some embodiments, the carrier member is configured to couple to a source of rotational power. Among other things, shift control interfaces for an IVT are disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/970,035, filed Aug. 19, 2013 and scheduled to issue as U.S. Pat. No.8,721,485 on May 13, 2014, which is a continuation of U.S. applicationSer. No. 13/035,683, filed Feb. 25, 2011, issued as U.S. Pat. No.8,512,195 on Aug. 20, 2013, which claims the benefit of U.S. ProvisionalPatent Application No. 61/310,224, filed Mar. 3, 2010. The disclosuresof all of the above-referenced prior applications, publications, andpatents are considered part of the disclosure of this application, andare incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the invention relates generally to transmissions, and moreparticularly the inventive embodiments related to continuously variabletransmissions (CVTs) and infinitely variable transmissions (IVTs).

2. Description of the Related Art

In certain systems, power is characterized by torque and rotationalspeed. More specifically, power in these systems is generally defined asthe product of torque and rotational speed. Typically, a transmissioncouples to a power input that provides an input torque at an inputspeed. The transmission also couples to a load that demands an outputtorque and output speed, which may differ from the input torque and theinput speed. Typically, and generalizing, a prime mover provides thepower input to the transmission, and a driven device or load receivesthe power output from the transmission. A primary function of thetransmission is to modulate the power input in such a way to deliver apower output to the driven device at a desired ratio of input speed tooutput speed (“speed ratio”).

Some mechanical drives include transmissions of the type known asstepped, discrete, or fixed ratio. These transmissions are configured toprovide speed ratios that are discrete or stepped in a given speed ratiorange. For example, such a transmission may provide for a speed ratio of1:2, 1:1, or 2:1, but such a transmission cannot deliver intermediatespeed ratios such as 1:1.5, 1:1.75, 1.5:1, or 1.75:1, for example. Otherdrives include a type of transmission generally known as a continuouslyvariable transmission (or “CVT”), which includes a continuously variablevariator. A CVT, in contrast to a stepped transmission, is configured toprovide every fractional ratio in a given speed ratio range. Forexample, in the speed ratio range mentioned above, a CVT is generallycapable of delivering any desired speed ratio between 1:2 and 2:1, whichwould include speed ratios such as 1:1.9, 1:1.1, 1.3:1, 1.7:1, etc. Yetother drives employ an infinitely variable transmission (or “IVT”). AnIVT, like a CVT, is capable of producing every speed ratio in a givenratio range. However, in contrast to a CVT, the IVT is configured todeliver a zero output speed (a “powered zero” state) with a steady inputspeed. Hence, given the definition of speed ratio as the ratio of inputspeed to output speed, the IVT is capable of delivering an infinite setof speed ratios, and consequently, the IVT is not limited to a givenratio range. It should be noted that some transmissions use acontinuously variable variator coupled to other gearing and/or clutchesin a split powered arrangement to produce IVT functionality. However, asused here, the term IVT is primarily understood as comprehending aninfinitely variable variator which produces IVT functionality withoutbeing necessarily coupled to additional gearing and/or clutches.

The field of mechanical power transmission is cognizant of continuous orinfinitely variable variators of several types. For example, one wellknown class of continuous variators is thebelt-and-variable-radius-pulley variator. Other known variators includehydrostatic, toroidal, and cone-and-ring variators. In some cases, thesevariators couple to other gearing to provide IVT functionality. Somehydromechanical variators can provide infinite ratio variability withoutadditional gearing. Some variators, continuously and/or infinitelyvariable, are classified as frictional or traction variators becausethey rely on dry friction or elastohydrodynamic traction, respectively,to transfer torque across the variator. One example of a tractionvariator is a ball variator in which spherical elements are clampedbetween torque transfer elements and a thin layer of elastohydrodynamicfluid serves as the torque transfer conduit between the spherical andthe torque transfer elements. It is to this latter class of variatorsthat the inventive embodiments disclosed here are most related.

There is a continuing need in the CVT/IVT industry for transmission andvariator improvements in increasing efficiency and packagingflexibility, simplifying operation, and reducing cost, size, andcomplexity, among other things. The inventive embodiments of the CVTand/or IVT methods, systems, subassemblies, components, etc., disclosedbelow address some or all of the aspects of this need.

SUMMARY OF THE INVENTION

The systems and methods herein described have several features, nosingle one of which is solely responsible for its desirable attributes.Without limiting the scope as expressed by the claims that follow, itsmore prominent features will now be discussed briefly. After consideringthis discussion, and particularly after reading the section entitled“Detailed Description of Certain Inventive Embodiments” one willunderstand how the features of the system and methods provide severaladvantages over traditional systems and methods.

One aspect of the invention relates to a shifting mechanism for aninfinitely variable transmission (IVT) having a longitudinal axis and aset of traction planet assemblies arranged angularly about thelongitudinal axis. In one embodiment, the shifting mechanism has a firstcarrier member coupled to each of the traction planet assemblies. Thefirst carrier member is configured to guide the traction planetassemblies. The shifting mechanism has a second carrier member coupledto each of the traction planet assemblies. The second carrier member isconfigured to guide the traction planet assemblies. The first carriermember is capable of rotating with respect to the second carrier member.A carrier driver nut is coupled to the first carrier member. The carrierdriver nut is adapted to translate axially. An axial translation of thecarrier driver nut corresponds to a rotation of the first carrier memberwith respect to the second carrier member.

One aspect of the invention relates to an infinitely variabletransmission (IVT) having a longitudinal axis. In one embodiment, theIVT has a number of traction planet assemblies arranged angularly aboutthe longitudinal axis. The IVT is provided with a first carrier membercoupled to each of the traction planet assemblies. The first carriermember is provided with a number of radially off-set slots. The firstcarrier member is configured to guide the traction planet assemblies.The IVT can include a second carrier member coupled to each of thetraction planet assemblies. The second carrier member is provided with anumber of radial slots. The first and second carrier members areconfigured to receive a rotational power input. In one embodiment, thefirst carrier member is capable of rotating with respect to the secondcarrier member. The IVT also includes a carrier driver nut coupled tothe first carrier member. The carrier driver nut is adapted to translateaxially. An axial translation of the carrier driver nut corresponds to arotation of the first carrier member with respect to the second carriermember. In an alternative embodiment, the IVT has a main shaftpositioned along the longitudinal axis. The main shaft is operablycoupled to the first and second carrier members. The main shaft can havea set of helical splines that are configured to couple to a carrierdriver nut. In yet another alternative embodiment, the carrier drivernut is adapted to translate axially along the main shaft. An axialtranslation of the carrier driver nut corresponds to a rotation of thecarrier driver nut. In some embodiments, the IVT has a first tractionring coupled to each traction planet assembly. The first traction ringis substantially non-rotatable about the longitudinal axis. The IVT canbe provided with a second traction ring coupled to each traction planetassembly. The second traction ring is adapted to provide a power outputfrom the IVT. In an alternative embodiment, the first and second carriermembers are adapted to receive the rotational power from the main shaft.In one embodiment, the IVT has a shift fork operably coupled to thecarrier driver nut. The shift fork can have a pivot axis that is off-setfrom the longitudinal axis. A pivoting of the shift fork corresponds toan axial translation of the carrier driver nut. The axial translation ofthe carrier driver nut corresponds to a rotation of the carrier driverabout the longitudinal axis. In an alternative embodiment, the IVT isprovided with a pump operably coupled to the main shaft. In yet anotherembodiment, the IVT has a ground ring coupled to the first tractionring. The ground ring is coupled to a housing of the IVT.

Another aspect of the invention concerns an infinitely variabletransmission (IVT) having a longitudinal axis. The IVT includes a mainshaft arranged along the longitudinal axis. The main shaft is providedwith a set of helical splines. The IVT has a group of traction planetassemblies arranged angularly about the longitudinal axis. In oneembodiment, the IVT has a first carrier member coupled to each of thetraction planet assemblies. The first carrier member is provided with anumber of radially off-set slots. The first carrier member is configuredto guide the traction planet assemblies. The IVT includes a secondcarrier member coupled to each of the traction planet assemblies. Thesecond carrier member is provided with a number of radial slots. Thefirst and second carrier members are coupled to a rotational powersource. In one embodiment, the IVT includes a shifting mechanism havinga shift fork. The shift fork has a pivot pin off-set from thelongitudinal axis. The shifting mechanism includes a carrier driver nutoperably coupled to the shift fork. The carrier driver nut has an innerbore configured to engage the helical splines of the main shaft. Thecarrier driver nut is configured to rotate about the longitudinal axis.In one embodiment, a movement of the shift fork about the pivot pincorresponds to an axial movement of the carrier driver nut. An axialmovement of the carrier driver nut corresponds to a rotation of thefirst carrier member with respect to the second carrier member. In someembodiments, the IVT has a first traction ring in contact with eachtraction planet assembly. The first traction ring is substantiallynon-rotatable about the main shaft. The IVT can have a second tractionring in contact with each traction planet assembly. The second tractionring is adapted to provide a power output from the IVT. In someembodiments, an output shaft is operably coupled to the second tractionring. In an alternative embodiment, a disengagement mechanism isoperably coupled to the output shaft. In yet another embodiment, atorque limiter is coupled to the second carrier member. The torquelimiter can also be coupled to the main shaft. In some embodiments, thetorque limiter includes a number of springs coupled to the secondcarrier member and the main shaft.

One aspect of the invention concerns a shifting mechanism for aninfinitely variable transmission (IVT) having a main shaft arrangedalong a longitudinal axis of the IVT and a group of traction planetassemblies arranged angularly about the main shaft. The traction planetassemblies are coupled to first and second carrier members. The firstcarrier member is provided with a number of radially off-set guideslots. The first and second carrier members are adapted to receive arotational power. In one embodiment, the shifting mechanism includes ashift fork. The shift fork has a pivot pin off-set from the longitudinalaxis. The shifting mechanism has a carrier driver nut operably coupledto the shift fork. The carrier driver nut has an inner bore configuredto engage a number of helical splines formed on the main shaft. Thecarrier driver nut is configured to rotate about the longitudinal axis.The carrier driver nut is adapted to axially translate along thelongitudinal axis. A movement of the shift fork about the pivot pincorresponds to an axial movement of the carrier driver nut. An axialmovement of the carrier driver nut corresponds to a rotation of thefirst carrier member with respect to the second carrier member. In analternate embodiment, the shifting mechanism includes a shift collaroperably coupled to the shift fork. A bearing can be coupled to theshift collar and be adapted to couple to the carrier driver nut. In yetanother embodiment, the shifting mechanism has a rocker arm coupled tothe shift fork.

Another aspect of the invention concerns an infinitely variabletransmission (IVT) having a longitudinal axis. The IVT has a group oftraction planets arranged angularly about the longitudinal axis. The IVTincludes a first carrier member coupled to each of the traction planetassemblies. The first carrier member is provided with a number ofradially off-set slots. The first carrier member is configured to guidethe traction planet assemblies. The IVT has a second carrier membercoupled to each of the traction planet assemblies. The second carriermember is provided with a group of radial slots. The first and secondcarrier members are coupled to a rotational power source. In oneembodiment, the IVT has a carrier driver positioned radially outward ofthe first and second carrier members. The carrier driver has a number oflongitudinal grooves. At least one groove is aligned parallel with thelongitudinal axis, and said groove is coupled to the first carriermember. In one embodiment, at least one groove is angled with respect tothe longitudinal axis, and said groove is coupled to the second carriermember. In other embodiments, the carrier driver is adapted to translateaxially. In some embodiments, the axial translation of the carrierdriver corresponds to a rotation of the first carrier member withrespect to the second carrier member. In still other embodiments, theIVT has a pump coupled to the first carrier member.

Another aspect of the invention relates to an infinitely variabletransmission (IVT) having a longitudinal axis. In one embodiment, theIVT has a number of traction planets arranged angularly about thelongitudinal axis. The IVT is provided with a first carrier membercoupled to each of the traction planet assemblies. The first carriermember is provided with a number of radially off-set slots. The radiallyoff-set slots are configured to guide the traction planet assemblies.The first carrier member is provided with a number of longitudinal guideslots, and said longitudinal guide slots are formed at an angle withrespect to the longitudinal axis. In one embodiment, the IVT has asecond carrier member coupled to each of the traction planet assemblies.The second carrier member is provided with a number of radial slots. Theradial slots are configured to guide the traction planet assemblies. Thesecond carrier member is provided with a number of longitudinal guideslots, and said longitudinal guide slots are arranged parallel to thelongitudinal axis. In one embodiment, the first and second carriermembers are configured to couple to a rotational power source. The IVTalso has a carrier driver coupled to the first and second carriermembers. The carrier driver is adapted to rotate about the longitudinalaxis. The carrier driver is adapted to translate axially. In oneembodiment, an axial translation of the carrier driver corresponds to arotation of the first carrier member with respect to the second carriermember. In some embodiments, the carrier driver has a set of shift pinsextending radially outward from a central cylindrical hub. Thecylindrical hub is coaxial with the longitudinal axis. In otherembodiments, the IVT has a spring coupled to the carrier driver. In yetother embodiments, an axial translation of the carrier drivercorresponds to a change in the transmission ratio of the IVT.

Another aspect of the invention concerns a shifting mechanism for aninfinitely variable transmission (IVT) having a group of traction planetassemblies. In one embodiment, the shifting mechanism has a firstcarrier member having a number of radially off-set guide slots. Theradially off-set guide slots are arranged to guide the traction planetassemblies. The first carrier member has a number of longitudinal slots,and said longitudinal slots angled with respect to the longitudinalaxis. The shifting mechanism includes a second carrier member has anumber of guide slots arranged about the longitudinal axis. The guideslots are arranged to guide the traction planet assemblies. The secondcarrier member has a number of longitudinal slots, and said longitudinalslots parallel to the longitudinal axis. The shifting mechanism has acarrier driver coupled to the first and second carrier members. Thecarrier driver has a number of shift pins extending from a central hub.The shift pins engage the longitudinal slots formed on the first andsecond carrier members. An axial translation of the carrier drivercorresponds to a rotation of the first carrier member with respect tothe second carrier member. In some embodiments, the carrier driver, thefirst carrier member, and the second carrier member are configured torotate about the longitudinal axis at a speed substantially equal to aninput speed of a power source coupled to the IVT. In other embodiments,the shifting mechanism has a shift roller coupled to each shift pin. Theshift roller is in contact with the longitudinal slots of the firstcarrier member.

Another aspect of the invention relates to a method of controlling aninfinitely variable transmission (IVT) having a longitudinal axis. Themethod includes the step of providing a group of traction planetassemblies arranged angularly about the longitudinal axis. The methodcan include providing a first carrier member coupled to each tractionplanet assembly. The first carrier member has a number of radiallyoff-set guide slots arranged to guide the traction planet assemblies. Inone embodiment, the method includes the step of providing a secondcarrier member coupled to each traction planet assembly. The secondcarrier member has a number of radial guide slots arranged to guide thetraction planet assemblies. The method can include the step of couplingthe first and second carrier members to a rotational power source. Themethod includes providing a carrier driver nut coupled to the firstcarrier member. The method also includes the step of translating thecarrier driver nut along the longitudinal axis. In an alternativeembodiment, the step of translating the carrier driver nut includes thestep of rotating the first carrier member with respect to the secondcarrier member. In some embodiments, the method includes the step ofoperably coupled the carrier driver nut to a shift fork. In someembodiments, the method includes the step of coupling a toque limiter tothe second carrier member. In yet other embodiments, the method includescoupling the torque limiter to the rotational source of power. In someembodiments, the method includes the step of sensing a torque applied tothe second carrier member. The method can also include the step ofrotating the second carrier member based at least in part on the sensedtorque. Rotating the second carrier member can include the step ofadjusting the transmission ratio.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view of a ball planetary infinitely variabletransmission (IVT) having a skew-based control system.

FIG. 2 is a partially cross-sectioned exploded view of the IVT of FIG.1.

FIG. 3 is a perspective view of internal components of the IVT of FIG.1.

FIG. 4 is a plan view of internal components of the IVT of FIG. 1.

FIG. 5 is an exploded view of shifting components that can be used withthe IVT of FIG. 1.

FIG. 6 is a plan view of an embodiment of first and second carriermembers that can be used in the IVT of FIG. 1.

FIG. 7 is a cross-sectional view of an infinitely variable transmission(IVT) having a skew-based control system.

FIG. 8 is a cross-sectional perspective view of the IVT of FIG. 7.

FIG. 9 is a cross-sectional view of an embodiment of a carrier driverring that can be used with the IVT of FIG. 7.

FIG. 10 is a perspective view of the carrier driver ring of FIG. 9.

FIG. 11 is a cross-sectional plan view of the carrier driver ring ofFIG. 9.

FIG. 12 is a cross-sectional plan view of one embodiment of a carrierdriver ring that can be used in the IVT of FIG. 7.

FIG. 13 is a cross-sectional plan view of another embodiment of acarrier driver ring that can be used in the IVT of FIG. 7.

FIG. 14 is a cross-sectional view of an IVT having a skew-based controlsystem and a carrier driver ring.

FIG. 15 is a schematic view of an embodiment of an IVT having askew-based control system and a linearly actuated carrier driver.

FIG. 16 is a cross-sectional view of one embodiment of an IVT having askew-based control system and a linearly actuated carrier driver.

FIG. 17 is a partially cross-sectioned perspective view of certaininternal shifting components of the IVT of FIG. 16.

FIG. 18 is a plan view of the internal shifting components of FIG. 17.

FIG. 19 is a plan view A-A of the internal shifting components of FIG.18.

FIG. 20 is a partially cross-sectioned perspective view of oneembodiment of an IVT having a skew-based control system.

FIG. 21 is a cross-sectional view of the IVT of FIG. 20.

FIG. 22 is an exploded, cross-sectioned view of the IVT of FIG. 20.

FIG. 23 is an exploded view of certain internal components of the IVT ofFIG. 20.

FIG. 24 is a cross-sectional view of a torque limiter that can be usedwith the IVT of FIG. 20.

FIG. 25 is an exploded view of the torque limiter of FIG. 24.

FIG. 26 is partially cross-sectioned view of a disengagement mechanismthat can be used with the IVT of FIG. 20.

FIG. 27 is a cross-sectional view of the disengagement mechanism of FIG.26.

FIG. 28 is another cross-sectional view of the disengagement mechanismof FIG. 26.

FIG. 29 is a cross-sectional view of an embodiment of a disengagementmechanism that can be used with the IVT of FIG. 1 or 20.

FIG. 30 is another cross-sectional view of the disengagement mechanismof FIG. 29.

FIG. 31 is a perspective view of a disengagement mechanism that can beused with the IVT of FIG. 20.

FIG. 32 is a cross-sectional view of the disengagement mechanism of FIG.31.

FIG. 33 is another perspective view of the disengagement mechanism ofFIG. 31.

FIG. 34 is yet another cross-sectional view of the disengagementmechanism of FIG. 31.

FIG. 35 is a schematic depicting a hydraulic system that can be usedwith the IVT of FIG. 20.

FIG. 36 is a cross-sectional view of one embodiment of an IVT having askew-based control system.

FIG. 37 is a plan view B-B of certain components of the IVT of FIG. 36.

FIG. 38 is a plan view of a carrier that can be used with the IVT ofFIG. 36.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

The preferred embodiments will be described now with reference to theaccompanying figures, wherein like numerals refer to like elementsthroughout. The terminology used in the descriptions below is not to beinterpreted in any limited or restrictive manner simply because it isused in conjunction with detailed descriptions of certain specificembodiments of the invention. Furthermore, embodiments of the inventioncan include several inventive features, no single one of which is solelyresponsible for its desirable attributes or which is essential topracticing the inventions described. Certain continuously variabletransmission (CVT) and infinitely variable transmission (IVT)embodiments described here are generally related to the type disclosedin U.S. Pat. Nos. 6,241,636; 6,419,608; 6,689,012; 7,011,600; 7,166,052;U.S. patent application Ser. Nos. 11/243,484 and 11/543,311; and PatentCooperation Treaty patent applications PCT/IB2006/054911,PCT/US2008/068929, PCT/US2007/023315, PCT/US2008/074496, andPCT/US2008/079879. The entire disclosure of each of these patents andpatent applications is hereby incorporated herein by reference.

As used here, the terms “operationally connected,” “operationallycoupled”, “operationally linked”, “operably connected”, “operablycoupled”, “operably linked,” and like terms, refer to a relationship(mechanical, linkage, coupling, etc.) between elements whereby operationof one element results in a corresponding, following, or simultaneousoperation or actuation of a second element. It is noted that in usingsaid terms to describe inventive embodiments, specific structures ormechanisms that link or couple the elements are typically described.However, unless otherwise specifically stated, when one of said terms isused, the term indicates that the actual linkage or coupling may take avariety of forms, which in certain instances will be readily apparent toa person of ordinary skill in the relevant technology.

For description purposes, the term “radial” is used here to indicate adirection or position that is perpendicular relative to a longitudinalaxis of a transmission or variator. The term “axial” as used here refersto a direction or position along an axis that is parallel to a main orlongitudinal axis of a transmission or variator. For clarity andconciseness, at times similar components labeled similarly.

It should be noted that reference herein to “traction” does not excludeapplications where the dominant or exclusive mode of power transfer isthrough “friction.” Without attempting to establish a categoricaldifference between traction and friction drives here, generally thesemay be understood as different regimes of power transfer. Tractiondrives usually involve the transfer of power between two elements byshear forces in a thin fluid layer trapped between the elements. Thefluids used in these applications usually exhibit traction coefficientsgreater than conventional mineral oils. The traction coefficient (μ)represents the maximum available traction forces which would beavailable at the interfaces of the contacting components and is ameasure of the maximum available drive torque. Typically, frictiondrives generally relate to transferring power between two elements byfrictional forces between the elements. For the purposes of thisdisclosure, it should be understood that the IVTs described here mayoperate in both tractive and frictional applications. For example, inthe embodiment where an IVT is used for a bicycle application, the IVTcan operate at times as a friction drive and at other times as atraction drive, depending on the torque and speed conditions presentduring operation.

Embodiments of the invention disclosed here are related to the controlof a variator and/or an IVT using generally spherical planets eachhaving a tiltable axis of rotation (sometimes referred to here as a“planet axis of rotation”) that can be adjusted to achieve a desiredratio of input speed to output speed during operation. In someembodiments, adjustment of said axis of rotation involves angularmisalignment of the planet axis in a first plane in order to achieve anangular adjustment of the planet axis of rotation in a second plane,thereby adjusting the speed ratio of the variator. The angularmisalignment in the first plane is referred to here as “skew” or “skewangle”. This type of variator control is generally described in U.S.patent application Ser. Nos. 12/198,402 and 12/251,325, the entiredisclosure of each of these patent applications is hereby incorporatedherein by reference. In one embodiment, a control system coordinates theuse of a skew angle to generate forces between certain contactingcomponents in the variator that will tilt the planet axis of rotation inthe second plane. The tilting of the planet axis of rotation adjusts thespeed ratio of the variator. Embodiments of skew control systems(sometimes referred to here as “skew based control systems”) and skewangle actuation devices for attaining a desired speed ratio of avariator will be discussed.

Embodiments of an infinitely variable transmission (IVT), and componentsand subassemblies thereof, will be described now with reference to FIGS.1-38. Embodiments of shifting mechanisms for controlling the relativeangular position between two disc-like transmission members will bedescribed as well. These shifting mechanisms can improve control formany different types of infinitely variable transmissions, and are shownin certain embodiments here for illustrative purposes. FIG. 1 shows anIVT 100 that can be used in many applications including, but not limitedto, human powered vehicles (for example, bicycles), light electricalvehicles, hybrid human-, electric-, or internal combustion poweredvehicles, industrial equipment, wind turbines, etc. Any technicalapplication that requires modulation of mechanical power transferbetween a power input and a power sink (for example, a load) canimplement embodiments of the IVT 100 in its power train.

Referring now to FIGS. 1 and 2, in one embodiment the IVT 100 includes ahousing 102 coupled to a housing cap 104. The housing 102 and thehousing cap 104 support a power input interface such as a pulley 106 anda control interface such as an actuator coupling 108. The pulley 106 canbe coupled to a drive belt driven by a source of rotational power suchas an internal combustion engine (not shown). In one embodiment, the IVT100 is provided with a main shaft 110 that substantially defines alongitudinal axis of the IVT 100. The main shaft 110 couples to thepulley 106. The main shaft 110 is supported by a bearing 112 in thehousing cap 104. The IVT 100 includes a plurality of traction planetassemblies 114 arranged angularly about the main shaft 110. Eachtraction planet assembly 114 is coupled to first and second carriermembers 116, 118, respectively. The main shaft 110 couples to the firstcarrier member 116. The first and second carrier members 116, 118 arecoaxial with the main shaft 110. In one embodiment, each traction planetassembly 114 is coupled to first and second traction rings 120, 122,respectively. Each traction planet assembly 114 is in contact with anidler assembly 121 at a radially inward location. The first tractionring 120 couples to a first axial force generator assembly 124. Thefirst traction ring 120 and the first axial force generator assembly 124is substantially non-rotatable with respect to the housing 102. In oneembodiment, the first axial force generator assembly 124 is coupled to aground ring 125. The ground ring 125 attaches to a shoulder 123extending from the housing cap 104. The second traction ring 122 iscoupled to a second axial force generator 126. The second traction ring122 and the second axial force generator 126 is coupled to an outputpower interface 128. The output power interface 128 can be coupled to aload (not shown). In one embodiment, the output power interface 128includes a disengagement mechanism 130 configured to mechanicallydecouple the second traction ring 122 from the load.

Referring now to FIGS. 1-4, in one embodiment the IVT 100 can be usedwith a shift control mechanism 140. The shift control mechanism 140 canbe used other types of transmissions, and is shown here with the IVT 100as an example. The shift control mechanism 140 can include the actuatorcoupling 108 coupled to a rocker arm 142. The rocker arm 142 couples toa shift fork 144 that is configured to rotate about a pivot pin 146. Inone embodiment, the pivot pin 146 is offset from the longitudinal axis.The shift fork 144 couples to a shift collar 148. The shift collar 148supports a bearing 150. The bearing 150 couples to a carrier driver nut152. The carrier driver nut 152 is coupled to the main shaft 110 and thefirst carrier member 116.

Referring now to FIG. 5 and still referring to FIGS. 1-4, in oneembodiment the rocker arm 142 rotatably couples to a pivot 143. Thepivot 143 can be a dowel attached to the shift fork 144. The shift fork144 can have a set of slots 154. The slots 154 guide a set of engagementdowels 156 attached to the shift collar 148. In one embodiment, theshift collar 148 is provided with four engagement dowels 156. In someembodiments, two engagement dowels 156 are positioned to ride in theslots 154 while two engagement dowels 156 are positioned to ride in aset of slots 155 (FIG. 2) formed in the shoulder 123 of the housing cap104. In one embodiment, the carrier driver nut 152 has an inner bore 158formed with helical splines. The inner bore 158 couples to matinghelical splines 160 formed on the main shaft 110. The carrier driver nut152 is provided with a number of guide surfaces 162 extending radiallyoutward from the inner bore 158. The guide surfaces 162 couple to matingguide surfaces 164 formed on the first carrier member 116.

Turning now to FIG. 6, in one embodiment the second carrier member 118can be provided with a number of guide slots 170 arranged angularlyabout a central bore 171. The guide slots 170 are aligned with a radialconstruction line 76 when viewed in the plane of the page of FIG. 6. Theguide slots 170 are adapted to receive one end of a planet axle 115(FIG. 1). In some embodiments, a radially inward portion 172 of theguide slots 170 are formed with curved profiles sized to accommodate thetraction planet axle 115. In one embodiment, the first carrier member116 is provided with a number of radially off-set guide slots 174arranged angularly about a central bore 175. Each radially off-set guideslot 174 is sized to accommodate the coupling of the first carriermember 116 to the planet axle 115. The radially off-set guide slots 174are angularly offset from the radial construction line 76 when viewed inthe plane of the page of FIG. 6. The angular offset can be approximatedby an angle 88. The angle 88 is formed between the radial constructionline 76 and a construction line 90. The construction line 90substantially bisects the radially off-set guide slot 174 when viewed inthe plane of the page of FIG. 6. In some embodiments, the angle 88 isbetween 3 degrees and 45 degrees. A low angle 88 produces a highlyresponsive transmission ratio change but potentially more difficult tocontrol or stabilize, while a high angle can be less responsive intransmission ratio change but easy to control by comparison. In someembodiments, where it is desirable to have high speed, fast shift rates,the angle 88 can be, for example, 10 degrees. In other embodiments,where it is desirable to have slower speed, precise control oftransmission ratio, the angle 88 can be about 30 degrees. However, thesaid values of the angle 88 are provided as an illustrative example, andthe angle 88 can be varied in any manner a designer desires. In someembodiments, the angle 88 can be any angle in the range of 10 to 25degrees including any angle in between or fractions thereof. Forexample, the angle 88 can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,21, 22, 23, 24, 25, or any portion thereof. In other embodiments, theangle 88 can be 20 degrees. In one embodiment, the radially off-setguide slots 174 can be arranged so that the construction line 90 isradially offset from a construction line 91 by a distance 92. Theconstruction line 91 is parallel to the construction line 90 andintersects the center of the first carrier member 116.

During operation of the IVT 100, a change in transmission ratio isachieved by rotating the actuator coupling 108. In some embodiments, theactuator coupling 108 is attached to a user control (not shown) that canbe a mechanical linkage actuated with a user's hand. In otherembodiments, the actuator coupling 108 can be coupled to an electricalor hydraulic actuator that can impart a rotary motion to the actuatorcoupling 108 that is indicative of the desired transmission ratio forIVT 100. Since the actuator coupling 108 is axially fixed with respectto the longitudinal axis, a rotation of the actuator coupling 108 tendsto rotate the rocker arm 142 to thereby rotate and axially translate thepivot 143. Movement of the pivot 143 tends to rotate the shift fork 144about the pivot pin 146. The pivot pin 146 is off-set from the mainshaft 110 so that a rotation of the shift fork 144 about the pivot pin146 corresponds to an axial translation of the slots 154. The axialmovement of the slots 154 tends to axially move the shift collar 148with respect to the main shaft 110. Since the carrier driver nut 152 isoperably coupled to the shift collar 148, an axial translation of theshift collar 148 corresponds to an axial translation of the carrierdriver nut 152. The carrier driver nut 152 couples to the helicalsplines 160 of the main shaft 110. An axial translation of the carrierdriver nut 152 facilitates a relative rotation of the carrier driver nut152 with respect to the main shaft 110. Since the carrier driver nut 152engages the guide surfaces 164 of the first carrier member 116, arotation of the carrier driver nut 152 with respect to the main shaft110 corresponds to a rotation of the first carrier member 116 withrespect to the main shaft 110. A rotation of the first carrier member116 with respect to the second carrier member 118 tends to change thetransmission ratio of the IVT 100.

It should be noted that a designer can configure the position of therocker 142, the pivot 143, and the pivot pin 146 relative to the slots154 to achieve a desired relationship between a rotation applied to theactuator coupling 108 and the axial displacement of the carrier drivernut 152. In some embodiments, a designer may select the position of therocker 142, the pivot 143, and the pivot pin 146 to provide a desiredforce or torque applied to the actuator coupling 108 to achieve a changein transmission ratio. Likewise, a designer can select the pitch andlead of the helical splines 160 to achieve a desired relationshipbetween an axial displacement of the carrier driver nut 152 and arotation of the first carrier member 116.

Referring again to FIGS. 5 and 6, in one embodiment the IVT 100 can beprovided with a pump assembly 180. The pump assembly 180 includes a pumpdriver 182 that couples to a lobe 184 formed on the first carrier member116. The pump assembly 180 includes a pump plunger 186 attached to thepump driver 182. The pump plunger 186 surrounds a valve body 188 and avalve plunger 190. In one embodiment, the lobe 184 has a center 191(FIG. 6) that is off-set from a center 192 of the first carrier member116. In some embodiments, the lobe 184 can be formed on main shaft 110or on a retaining nut 193, and likewise, the pump assembly 180 isappropriately located axially so that the pump driver 182 can engage thelobe 184. During operation of the IVT 100, the main shaft 110 rotatesabout the longitudinal axis and thereby drives the first carrier member116. The lobe 184 drives the pump driver 182 in a reciprocating motionas the first carrier member 116 rotates about the longitudinal axis. Inone embodiment, the ground ring 125 is provided with a guide groove 194that is adapted to receive the pump driver 182. The ground ring 125 canalso be provided with a number of clearance reliefs 196 that areappropriately sized to provide clearance to the engagement dowels 156and the shift fork 144.

Passing now to FIGS. 7-10, an IVT 200 can include a number of tractionplanet assemblies 202 arranged angularly about a longitudinal axis 204.For clarity, the housing and some internal components of the IVT 200 arenot shown. Each traction planet assembly 202 is provided with a ballaxle 206. The ball axles 206 are operably coupled to first and secondcarrier members 208, 210, respectively. The first and second carriermembers 208, 210 can be substantially similar to the first and secondcarrier members 116, 118, respectively. In one embodiment, the first andsecond carrier members 208, 210 couple to a rotational power source (notshown). The IVT 200 is provided with a carrier driver ring 212 locatedradially outward of each of the traction planet assemblies 202. Thecarrier driver ring 212 is couple to a shift clevis 214 by a set ofbearings 215. The bearing 215 can be rotationally constrained to thecarrier drive ring 212 with a plurality of dowels 217, for example. Inone embodiment, the shift clevis 214 is provided with a threaded bore213. The threaded bore 213 is generally parallel to the longitudinalaxis 204. The threaded bore 213 can couple to a threaded shift rod (notshown) to facilitate the axial translation of the shift clevis 214.

Referring specifically to FIGS. 9 and 10, the carrier driver ring 212has a set of longitudinal grooves 220 formed on an inner circumferenceof the carrier driver ring 212. The longitudinal grooves 220 aresubstantially parallel to the longitudinal axis 204. The carrier driverring 212 has a set of off-set longitudinal grooves 222 formed on theinner circumference. The off-set longitudinal grooves 222 are angledwith respect to the longitudinal axis 204. The off-set longitudinalgrooves 222 form an angle 224 with respect to the longitudinal axis 204when viewed in the plane of FIG. 9. In some embodiments, the angle 224can be any angle in the range of 0 to 30 degrees including any angle inbetween or fractions thereof. For example, the angle 224 can be 0, 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,23, 24, 25, 26, 27, 28, 29, 30 or any portion thereof. In oneembodiment, the first carrier member 208 is provided with a number ofdowels 228. The dowels 228 couple to, and are guided by, thelongitudinal grooves 220. The second carrier member 210 is provided witha number of dowels 230. The dowels 230 couple to, and are guided by, theoff-set longitudinal grooves 222.

During operation of the IVT 200, a change in transmission ratio can beachieved by axially translating the shift clevis 214. An axialtranslation of the shift clevis 214 tends to axially translate thecarrier driver ring 212. An axial translation of the carrier driver ring212 tends to guide the dowels 228, 230 in the grooves 220, 222,respectively. Since the first and second carrier members 208, 210 aresubstantially fixed in the axial direction, the first and second carriermembers 208, 210 rotate relative to each other as the dowels 228, 230travel axially in the grooves 220, 222, respectively.

Referring specifically now to FIGS. 11-13, the longitudinal groovesformed on the carrier driver ring 212 can take many forms in order toprovide the desired relative rotation of the first carrier member 208with respect to the second carrier member 210. For example, FIG. 11shows the longitudinal groove 220 and the off-set longitudinal groove222. On one side of the carrier driver ring 212 the grooves 220, 222 areseparated by a distance 232. On the opposite side of the carrier driverring 212, the grooves 220, 222 are separated by a distance 234. In theembodiment illustrated in FIG. 12, the carrier driver ring 212 isprovided with the longitudinal grooves 220 and a set of curved groove236. In the embodiment illustrated in FIG. 13, the carrier driver ring212 is provided with a set of positively off-set longitudinal grooves238 and a set of negatively off-set longitudinal grooves 240. It shouldbe noted that the embodiments described here are for illustrativepurposes and the shape and dimensions of the grooves formed on thecarrier ring 212 can be configured by a designer to achieve a desiredshift performance. For example, the 232 distance between thelongitudinal grooves 220 and the off-set longitudinal grooves 222 can beless than the distance 234 on an opposite side of the carrier driverring 212. The difference between the distances 232, 234 can beconfigured to produce a desired rotation of the first carrier member 208with respect to the second carrier member 210 over an axial displacementof the carrier driver ring 212 along the longitudinal axis 204.

Passing now to FIG. 14, in one embodiment an IVT 300 can besubstantially similar to the IVT 200. The IVT 300 can include a housing302 configured to substantially enclose internal components of the IVT300. The IVT 300 can be provided with a carrier driver ring 304. Thecarrier driver ring 304 can be coupled to the first and second carriermembers 208, 210 in a similar manner as the carrier driver ring 212. Thecarrier driver ring 304 can be configured to translate axially by anactuator such as a motor (not shown). In one embodiment, the carrierdriver ring 304 is radially supported on an output ring 306. The outputring 306 is operably coupled to each of the traction planet assemblies202.

Turning now to FIG. 15, in one embodiment an IVT 400 can have a numberof traction planet assemblies 402 arranged angularly about a main shaft404. Each traction planet assembly 402 couples to first and secondtraction rings 406, 408, respectively. Each traction planet assembly 402couples to an idler assembly 410. The idler assembly 410 is locatedradially inward of each traction planet assembly 402. In one embodiment,each traction planet assembly 402 is coupled to first and second carriermembers 412, 414. The first and second carrier members 412, 414 can besubstantially similar to the first and second carrier members 116, 118,respectively. In one embodiment, the first carrier member 412 is rigidlyattached to the main shaft 404. The first and second carrier members412, 414 and the main shaft 404 can be adapted to operably couple to asource for rotational power (not shown). The second carrier member 414is adapted to rotate with respect to the first carrier member 412. Inone embodiment, the second carrier 414 is coupled to a torsion plate416. The torsion plate 416 is coaxial with the second carrier 414 andcan be rigidly attached to the second carrier plate 414 with splines,weld, or other appropriate fastening means. In one embodiment, thetorsion plate 416 is rigid or stiff in a rotational direction but has adegree of flexibility in the axial direction, as is common among torsionplates. This degree of flexibility in the axial direction provides aspring-like compliance to the torsion plate 416. The torsion plate 416is coupled to a carrier driver nut 418 at a radially inward location.The carrier driver nut 418 has an inner bore formed with helical splines420 that are arranged to engage mating helical splines formed on themain shaft 404. The carrier driver nut 418 is operably coupled to anactuator coupling 422. In one embodiment, the actuator coupling 422 iscoupled to a linear actuator such as a servo motor or manual lever (notshown) that produces a force depicted as a vector 424 in FIG. 15. In oneembodiment, the actuator coupling 422 is substantially non-rotatableabout the main shaft 404.

During operation of the IVT 400, a change in transmission ratio isachieved by axially translating actuator coupling 422. An axialtranslation of the actuator coupling 422 tends to axially translate thecarrier driver nut 418. Since the carrier driver nut 418 engages themain shaft 404 on helical splines 420, an axial translation of thecarrier driver nut 418 with respect to the main shaft 404 tends tofacilitate a relative rotation between the carrier driver nut 418 andthe main shaft 404. The torsion plate 416 rotates as the carrier drivernut 418 rotates, which tends to rotate the second carrier member 414with respect to the first carrier member 412.

Referring now to FIGS. 16-19, in one embodiment an IVT 500 can beprovided with a number of traction planet assemblies 502 in contactwith, and radially outward of an idler assembly 504. Each tractionplanet assembly 502 is in contact with first and second traction rings506, 508, respectively. In one embodiment, the first traction ring 506is substantially non-rotatable. The IVT 500 can be provided with anoutput shaft 510. The output shaft 510 couples to a common axial forcegenerator coupling 512, which is configured to engage the secondtraction ring 508. Each traction planet assembly 502 is guided andsupported by first and second carrier members 514, 516, respectively.The first and second carrier members 514, 516 are provided with guideslots 513, 515, respectively. In one embodiment, the guide slots 513,515 are substantially similar to guide slots 170, 174, respectively. Thefirst and second carrier members 514, 516 are adapted to receive a powerinput from a rotational power source (not shown). In one embodiment, aninput shaft 518 can be coupled to a drive gear 520 that engages acarrier gear 522. The carrier gear 522 facilitates the transfer of powerto the first and second carrier members 514, 516. The output shaft 510can be supported by a bearing, for example, on the housing 524. In oneembodiment, the housing 524 is formed with two parts that are fastenedtogether to substantially enclose the internal components of the IVT500.

In one embodiment, the IVT 500 is provided with a center shaft 526 thatsubstantially defines a longitudinal axis of the IVT 500. The centershaft 526 can be configured to support the first and second carriermembers 514, 516. In some embodiments, the second carrier member 516 isrigidly attached to the center shaft 526. The first carrier member 514can be piloted onto the center shaft 526 so that the first carriermember 514 can rotate with respect to the second carrier member 516. Oneend of the center shaft 526 can be configured to support an actuatorcoupling 528. In one embodiment, a bearing 529 supports the actuatorcoupling 528 on the center shaft 514. The bearing 529 is configured toallow axial translation of the actuator coupling 528 with respect to thecenter shaft 526. The actuator coupling 528 is attached to the housing524 with splines and is substantially non-rotatable with respect to thecenter shaft 526. In one embodiment, the actuator coupling 528 iscoupled to a linear actuator (not shown) to facilitate an axialtranslation of the actuator coupling 528. The actuator coupling 528couples with a bearing 530 to a carrier driver hub 532. The carrierdriver hub 532 couples to the first and second carrier members 514, 516.

Referring now specifically to FIGS. 17-19, the carrier driver hub 532can be provided with a number of rods 534 extending from a substantiallycylindrical body. Each of the rods 534 is provided with a roller 536.The rods 534 engage a number of longitudinal slots 538 formed on thesecond carrier member 516. The rollers 536 engage a number oflongitudinal slots 540 formed on the first carrier member 514. Thelongitudinal slots 538 are substantially parallel with the longitudinalaxis of IVT 500. The longitudinal slots 540 are angled with respect tothe longitudinal axis of IVT 500 when viewed in the plane of the page ofFIG. 19.

During operation of the IVT 500, a change in transmission ratio isachieved by axially translating the actuator coupling 528. The axialtranslation of the actuator coupling 528 tends to axially translate thecarrier driver hub 532. As the carrier driver hub 532 translatesaxially, the rods 534 and rollers 536 axially translate along thelongitudinal slots 538, 540, respectively. Since the longitudinal slots540 are angled with respect to the longitudinal slots 540, an axialtranslation of the rods 534 and rollers 536 causes a relative rotationbetween the first carrier member 514 and the second carrier member 516,and thereby tends to change the ratio of the IVT 500. In someembodiments, the IVT 500 can be provided with a spring 542 configured tourge the carrier driver hub 532 to one axial end of the IVT 500.

Referring now to FIGS. 20 and 21, in one embodiment an IVT 600 includesa housing 602 coupled to a housing cap 604. The housing 602 and thehousing cap 604 support a power input interface such as a pulley 606 anda shift actuator 608. The pulley 606 can be coupled to a drive beltdriven by a source of rotational power such as an internal combustionengine (not shown). In one embodiment, the IVT 600 is provided with amain shaft 610 that substantially defines a longitudinal axis of the IVT600. The main shaft 610 couples to the pulley 606. The IVT 600 includesa plurality of traction planet assemblies 614 coupled to first andsecond carrier members 616, 618, respectively. The first and secondcarrier members 616, 618 are provided with guide slots that aresubstantially similar to the guide slots 170 and the radially offsetguide slots 174. In one embodiment, the first and second carrier members616, 618 have a thin and substantially uniform cross-section when viewedin the plane of the page of FIG. 21, which allows various manufacturingtechniques, such as sheet metal stamping, to be employed in themanufacture of the first and second carrier members 616, 618.

Still referring to FIGS. 20 and 21, in one embodiment, the main shaft610 couples to the first carrier member 616. Each traction planetassembly 614 is in contact with first and second traction rings 620,622, respectively. Each traction planet assembly 614 is in contact withan idler assembly 621 at a radially inward location. The second tractionring 622 couples to an axial force generator 624. The axial forcegenerator 624 couples to an output driver 626. In one embodiment, thefirst traction ring 620 couples to a ground ring 625 and issubstantially non-rotatable with respect to the housing 602. The IVT 600has an output shaft 627 coupled to the output driver 626. The outputshaft 627 delivers a rotational power from the IVT 600. In oneembodiment, the output shaft 627 is supported in the housing 602 by anangular contact bearing 628 and a radial ball bearing 629 (see forexample, FIG. 23). In some embodiments, a shaft seal 631 can be coupledto the output shaft 627 and the housing 602.

In some embodiments, the IVT 600 can be provided with a torque limiter630 that couples to the second carrier member 618 and the main shaft610. The IVT 600 can also be provided with a pump assembly 635 coupledto the main shaft 610 (see for example, FIG. 22). In one embodiment, thepump assembly 635 can use a gerotor type pump to pressurize transmissionfluid and distribute it to internal components of the IVT 600. The pumpassembly 635 can be appropriately equipped with hoses and/or lines toroute transmission fluid. During operation of the IVT 600, the pumpassembly 635 is driven by the main shaft 610.

Referring now to FIGS. 22 and 23, in one embodiment the IVT 600 isprovided with a shift control mechanism 640. The shift control mechanism640 can be used on other types of transmission and is shown here withthe IVT 600 as an example. The shift control mechanism 640 can includean actuator linkage 642 coupled to the shift actuator 608. The shiftactuator 608 can be coupled to a shift fork 644. In one embodiment, theshift actuator 608 is configured to pivot the shift fork 644 about anaxis 646. In one embodiment, the axis 646 is offset from thelongitudinal axis of the IVT 600. The shift fork 644 can be supported inthe housing cap 604. The shift fork 644 can be coupled to a shift collar648. The shift collar 648 supports a bearing 650. The shift fork 644 andthe shift collar 648 can be coupled, for example, with pins 651. Theshift fork 644 and the shift collar 648 are substantially non-rotatableabout the longitudinal axis of the IVT 600. In one embodiment, the shiftcontrol mechanism 640 includes a carrier driver nut 652. The carrierdriver nut 652 couples to the main shaft 610 through a set of helicalsplines 654. The carrier driver nut 652 couples to the first carriermember 616 through a carrier extension 656. In one embodiment thecarrier extension 656 has a set of axial guide slots that are configuredto engage the carrier driver nut 652.

During operation of the IVT 600, a shift in the transmission ratio canbe achieved by moving the actuator linkage 642 to thereby rotate theshift actuator 608. A rotation of the shift actuator 608 corresponds topivoting of the shift fork 644 about the axis 646. The pivoting of theshift fork 644 urges the shift collar 648 axially with respect to themain shaft 610. The shift collar 648 thereby axially translates thebearing 650 and carrier driver nut 652. The helical splines 654 tend torotate the carrier driver nut 652 as the carrier driver nut 652 movesaxially. The rotation of the carrier driver nut 652 is typically a smallangle. The carrier extension 656, and consequently the first carriermember 616, is guided through a rotation by the carrier driver nut 652.As explained previously in reference to FIG. 6, a rotation of the firstcarrier member 616 with respect to the second carrier member 618 causesa shift in the transmission ratio of the IVT 600.

In one embodiment, the helical splines 654 have a lead in the range of200-1000 mm. For some applications, the lead is in the range of 400-800mm. The lead is related to how much friction is in the system that cancounteract a phenomenon known as back torque shifting. The lead can besized to reduce the input force on the carrier driver nut 652, therequired rotation of the first carrier member 616 to shift through theratio, and available package space. The sizing of the lead is subject todesign requirements, and could also be impacted by testing results.

Turning now to FIGS. 24 and 25, in one embodiment the IVT 600 can beprovided with a torque limiter 630 coupled to the second carrier member618. The torque limiter 630 can be used with other types oftransmissions and is shown here with the IVT 600 as an example. Thesecond carrier member 618 is provided with a piloting shoulder 660 thatis configured to pilot to the main shaft 610. The second carrier member618 has a number of openings 662 arranged radially about the pilotingshoulder 660. The openings 662 are sized appropriately to couple to aplurality of springs 664. In one embodiment, the springs 664 are coilsprings having end caps 666. The torque limiter 630 includes a springcarrier 668. The springs 664 are coupled to the spring carrier 668. Insome embodiments, a number of retaining dowels 670 are provided on thespring carrier 668 to mate with each end cap 666 in order to facilitateretaining the springs 664 on the spring carrier 668. The spring carrier668 couples to the main shaft 610 with a splined inner bore 672.

In one embodiment, the torque limiter 630 includes a carrier cap 676coupled to the second carrier member 618. In some embodiments, thespring carrier 668 is axially located between the second carrier member618 and the carrier cap 676. The carrier cap 676 can be provided with anumber of tabs 678 to facilitate attachment to the second carrier member618 with, for example, rivets 679. The carrier cap 676 can be providedwith a number of openings 680 arranged radially about a pilotingshoulder 682. In one embodiment, the piloting shoulder 682 cooperateswith a mating shoulder 684 formed on the spring carrier 668.

During operation of the IVT 600, torque can be limited to apredetermined value by using the torque limiter 630. The main shaft 610is adapted to receive a rotational power from the pulley 606. Therotational power is transferred to the 25 first carrier member 616 andthe spring carrier 668. The spring carrier 668 transfers the rotationalpower to the second carrier member 618 via the springs 664. The springs664 are sized appropriately so that the springs 664 deflect when anoutput torque is above a predetermined value or in the case when atorque on the second carrier member 618 is above a predetermined value.The deflection of springs 664 corresponds to a rotation of the secondcarrier member 618 with respect to the first carrier member 616 therebyshifting the transmission ratio. The shift in transmission ratio reducesthe torque on the second carrier member 618.

Turning now to FIGS. 26-29, in one embodiment, the IVT 600 can beprovided with a disengagement mechanism 700. The disengagement mechanism700 can be used with other types of transmissions and is shown here withthe IVT 600 as an example. In one embodiment, the disengagementmechanism 700 includes a outer ring 702 coupled to a coupling ring 704.The coupling ring 704 is attached to the traction ring 620. In someembodiments, the outer ring 702 and the coupling ring 704 replace theground ring 625. The outer ring 702 couples to the housing 602 andhousing cap 604. In some embodiments, an actuator (not shown) couples tothe outer ring 702. For example, the actuator can be a lever (not shown)that extends through the housing 602 to thereby enable the outer ring702 to be rotated. The outer ring 702 is provided with a number of ramps706 about the inner circumference. The ramps 706 couple to a set ofsplines 708 formed on the outer periphery of the inner ring 704. Duringoperation of the IVT 600, decoupling of the input from the output can beachieved by rotating the outer ring 706. The rotation of the outer ring706 corresponds to an axial displacement of the traction ring 620 fromthe traction planet assemblies 614.

Passing now to FIGS. 29-30, in one embodiment, the IVT 600 can beprovided with a disengagement mechanism 800. The disengagement mechanism800 can be used with other types of transmissions and is shown here withthe IVT 600 as an example. In some embodiments, the disengagementmechanism 800 has a drive shaft 802 that can be selectively coupled toan output shaft 804 using a coupling 806. Once assembled the drive shaft802 and the output shaft 804 can be used in place of the output shaft627. The coupling 806 is configured to engage a set of splines 808formed on an inner diameter of the output shaft 804. In someembodiments, a spring (not shown) can 26 be inserted between thecoupling and the output shaft 804. The spring tends to bias the coupling806 to the position depicted in FIG. 29, which is an engaged position.The coupling 806 is attached to a cable pull 810. The cable pull 810 canbe supported on an internal bore of the coupling 806 by a bearing 812.The cable pull 810 can be attached to a push-pull cable (not shown). Thecable can be coupled to an external linkage that can be actuated totension the cable and move the coupling 806 axially. A cable guide 814provides a path through which the cable can enter the inner bore of theoutput shaft 814 without interference. The cable guide 814 is supportedwith a bearing 816. During operation of the IVT 600, the output shaft804 can be selectively coupled to an engaged position, as illustrated inFIG. 30, by tensioning the cable (not shown) and axially translating thecoupling 806.

Referring now to FIGS. 31-34, in one embodiment, the IVT 600 can beprovided with a disengagement mechanism 900. The disengagement mechanism900 can be used with other types of transmissions and is shown here withthe IVT 600 as an example. In one embodiment, the disengagementmechanism 900 can replace the output shaft 627. The disengagementmechanism 900 can include an elongated shaft 902 suitably configured tobe supported in the housing 602 by bearings 628, 629 and seal 630. Theelongated shaft 902 can have a first end 901 and a second end 903. Thefirst end 901 can be adapted to couple to an output load with, forexample, a keyway or other fastening means. The second end 903 of theshaft 902 is provided with a number of retractable teeth 904. Theretractable teeth 904 are positioned radially about the circumference ofthe end 903. The retractable teeth 904 can be inserted between, andretained by axial extensions 906 formed on the end 903. The retractableteeth 904 are operably coupled to a sliding member 908. The slidingmember 908 is coupled to an actuator coupling 910. The sliding member908 guides the retractable teeth 904 to either an engaged position or adisengaged position. In one embodiment, the retractable teeth can 904can be coupled to a spring member (not shown) that is configured to biasthe retractable teeth 904 to a position depicted in FIGS. 31 and 32. Insaid position, the retractable teeth 904 can engage, for example, theoutput driver 626. An actuator (not shown) can be configured to coupleto the actuator coupling 910 through an inner bore of the shaft 902 tofacilitate movement of the sliding member 908 and correspondingly movethe teeth 904 to a second position depicted in FIGS. 33 and 34. In saidposition, the teeth 904 are displaced radially so that the output driver626 is decoupled from the shaft 902.

Turning now to FIG. 35, in one embodiment, a hydraulic system 950 can beused with the IVT 100, the IVT 600, or other embodiments oftransmissions. The hydraulic system 950 includes a sump 952 having afill depth 954. In some embodiments, the sump 952 is formed into a lowerportion of the housing 602, for example. For illustration purposes,rotating components of the IVT 600 are depicted as rotating components955 in FIG. 35. The hydraulic system 950 includes a pump 956 that can besubstantially similar to the pump assembly 635, for example. The pump956 transports fluid from the sump 952 to a reservoir 958. In oneembodiment, the reservoir 958 is provided with a first orifice 960 and asecond orifice 962. The first orifice 960 is positioned above the secondorifice 960. The reservoir 958 is located above the rotating components955 and the sump 952. In one embodiment, the reservoir 958 can be formedon the housing 602, for example. In other embodiments, the reservoir 958is attached to the outside of the housing 602 and configured to havefluid communication with the rotating components 958 and the sump 952.

During assembly of the IVT 600, for example, a fluid is added to thesump 952. In some embodiments, the volume of the sump 952 can be small,therefore variation in the fluid volume added to the sump 952 can have asignificant influence on the fill depth 954. In some instances, the filldepth 954 can be high enough to cause fluid in the sump 952 to contactthe rotating components 955. Contact between the fluid in the sump 952and the rotating components 955 can create drag and windage, which areknown to be problematic. However, in certain instances, it may bedesirable to increase the volume of fluid added to the sump 952. Forexample, increasing the volume of fluid may improve thermalcharacteristics, durability, and maintenance. Therefore, the hydraulicsystem 952 can be implemented to facilitate the increase in fluid volumeadded to the sump 952 and maintain a fill depth 954 below the rotatingcomponents 955.

During operation of the IVT 600, for example fluid is drawn from thesump 952 by the pump 956, which lowers the fill depth 954. The fluid ispressurized and delivered by the pump 956 to the reservoir 958. Thereservoir 958 receives pressurized fluid and fills the volume of thereservoir 958. The first and second orifices 960, 962 are sizedappropriately so that once the reservoir 958 is under pressure, fluidcan flow from the first orifice 960 while substantially no fluid flowsfrom the second orifice 962. In some embodiments, the second orifice 962can be a check valve that is configured to be open when the reservoir958 is depressurized, and closed when the reservoir 958 is pressurized.The fluid flow from the first orifice 960 is directed to the rotatingcomponents 955 to provide lubrication and cooling. During operation ofthe IVT 600, for example, the reservoir 958 accumulates a volume offluid. Once operation of the IVT 600 ceases, the accumulated volumedrains from the reservoir 958 and returns to the sump 952.

Referring now to FIGS. 36-38, in one embodiment an IVT 1000 can besubstantially similar to the IVT 100. For clarity, only certain internalcomponents of the IVT 1000 are shown. In one embodiment, the IVT 1000includes a number of balls 1001 arranged angularly about a longitudinalaxis 1002. Each ball 1001 is configured to rotate about an axle 1003that forms a tiltable axis. One end of the axle 1003 is provided with aspherical roller 1004. An opposite end of the axle 1003 is coupled to aguide block 1005 with, for example, a pin 1010. In one embodiment, theguide block 1005 has an extension 1006. The IVT 1000 can include a firstcarrier member 1007 that is substantially similar to the carrier member118. The first carrier member 1007 is configured to couple to thespherical rollers 1004 to provide the axles 1003 with a suitable degreeof freedom. The IVT 1000 can include a second carrier member 1008 thatis configured to operably couple to the guide blocks 1005. The IVT 100is provided with a shifting plate 1012 arranged coaxially with the firstand second carrier members 1007, 1008. The shifting plate 1012 couplesto the extensions 1006. In one embodiment, the shifting plate 1012 canbe actuated with, for example, the shift control mechanism 140. Theshifting plate 1012 is configured to rotate relative to the first andsecond carrier members 1007, 1008.

Referring specifically now to FIG. 38, in one embodiment, the shiftingplate 1012 is provided with a number of slots 1014. The extensions 1006couple to the slots 1014. For illustration purposes, only one of theslots 1014 is shown. The slot 1014 can be illustrated as having threeportions: a first portion 1015, a middle portion 1016, and a thirdportion 1017. The middle portion 1016 can be defined as the arc lengthbetween a set of radial construction lines 1018, 1019, respectively. Thefirst portion 1015 and the third portion 1017 are angularly off-set fromthe radial construction lines 1018, 1019, respectively, in asubstantially similar way as the radially off-set slots guide slots 174are offset from the radial construction line 76. During operation of theIVT 1000, a change in transmission ratio can be achieved by rotating theshifting plate 1012 with respect to the first and second carrier members1007, 1008. The extensions 1006 are guided by the slots 1014. When theextension 1006 is positioned in the first portion 1015 of the slot 1014,the transmission ratio can be a forward or positive ratio. When theextension 1006 is positioned in the third portion 1017 of the slot 1014,the transmission ratio can be a reverse or negative ratio. When theextension 1006 is positioned in the middle portion 1016, thetransmission ratio is in neutral or a condition referred to as“powered-zero.” The dimensions of the slot 1014 can be appropriatelysized to accommodate a desired relationship between a change in thetransmission ratio and a change in, for example, a change in an actuatorposition.

It should be noted that the description above has provided dimensionsfor certain components or subassemblies. The mentioned dimensions, orranges of dimensions, are provided in order to comply as best aspossible with certain legal requirements, such as best mode. However,the scope of the inventions described herein are to be determined solelyby the language of the claims, and consequently, none of the mentioneddimensions is to be considered limiting on the inventive embodiments,except in so far as any one claim makes a specified dimension, or rangeof thereof, a feature of the claim.

The foregoing description details certain embodiments of the invention.It will be appreciated, however, that no matter how detailed theforegoing appears in text, the invention can be practiced in many ways.As is also stated above, it should be noted that the use of particularterminology when describing certain features or aspects of the inventionshould not be taken to imply that the terminology is being re-definedherein to be restricted to including any specific characteristics of thefeatures or aspects of the invention with which that terminology isassociated.

What we claim is:
 1. An infinitely variable transmission (IVT) having alongitudinal axis, the IVT comprising: a main shaft coaxially arrangedalong the longitudinal axis, the main shaft provided with a plurality ofhelical splines; a plurality of traction planet assemblies arrangedangularly about the longitudinal axis; a first carrier member coupled toeach of the traction planet assemblies, the first carrier member havinga plurality of radially off-set slots, the first carrier member beingconfigured to guide the traction planet assemblies; a second carriermember coupled to each of the traction planet assemblies, the secondcarrier member provided with a plurality of radial slots, wherein thefirst and second carrier members are coupled to a rotational powersource; a first traction ring in contact with each traction planetassembly, the first traction ring being substantially non-rotatableabout the main shaft; a second traction ring in contact with eachtraction planet assembly; a torque limiter coupled to the second carriermember; and a shifting mechanism comprising a shift fork having a pivotpin off-set from the longitudinal axis; and a carrier driver nutoperably coupled to the shift fork, the carrier driver nut having aninner bore configured to engage the helical splines of the main shaft,the carrier driver nut configured to rotate about the longitudinal axis,wherein a movement of the shift fork about the pivot pin corresponds toan axial movement of the carrier driver nut, and wherein an axialmovement of the carrier driver nut corresponds to a rotation of thefirst carrier member with respect to the second carrier member.
 2. TheIVT of claim 1, wherein the torque limiter comprises a plurality ofsprings coupled to the second carrier member and the main shaft.
 3. TheIVT of claim 1, further comprising an actuator coupling for rotating theshift fork about the pivot pin, wherein the actuator coupling comprisesa mechanical linkage.
 4. The IVT of claim 1, further comprising anactuator coupling for rotating the shift fork about the pivot pin,wherein the actuator coupling comprises an electrical or hydraulicactuator.
 5. The IVT of claim 1, wherein the second traction ring isadapted to provide a power output from the IVT.
 6. The IVT of claim 1,wherein the torque limiter is coupled to the rotational power source. 7.The IVT of claim 1, further comprising a controller operable to sense atorque applied to the second carrier member and to rotate the secondcarrier member based at least in part on the sensed torque.
 8. The IVTof claim 1, wherein rotating the first carrier member with respect tothe second carrier member comprises controlling the angular positionbetween the first and second carrier members.
 9. The IVT of claim 1,wherein the first carrier member comprises curved radially off-set guideslots.
 10. The IVT of claim 1, wherein the second carrier membercomprises curved radial guide slots.
 11. The IVT of claim 1, wherein thefirst carrier member comprises radially positive off-set guide slots.12. The IVT of claim 1, wherein the first carrier member comprisesradially negative off-set guide slots.